For a radio control device that uses a radio frequency link to transmit commands to a radio controlled unit such as a model car, a user operates a radio control transmitter in order to remotely control the commands transmitted to the radio controlled unit. The transmitted commands control the operating range of a speed control servo and a direction control servo placed in the radio controlled unit, thereby enabling remote control thereof. One of such conventional radio control transmitters is illustrated in FIG. 8. (The transmitter shown in FIG. 8 is intended for a right-handed user) Such conventional radio control transmitter is of a wheel type including a grip handle 1, a main body 2, a throttle trigger 3, a steering wheel 4, an antenna 5, a battery case 6, and a display 7. Ordinarily, the user grips the handle 1 with the left hand in a manner similar to gripping a pistol and places the index finger on the throttle trigger 3, whereas the right hand is placed on the wheel 4 disposed in the center of a front face the main body 2. In case of operating a radio controlled unit, e.g., a model car, by employing such radio control transmitter, the throttle trigger 3 can be squeezed with varying degree in the direction of arrow A to move the radio controlled unit forward at a speed corresponding to the squeezed degree. And when the throttle trigger 3 is pushed forward in the direction of arrow B, the controlled unit moves backward at a speed corresponding to the amount of push or, in case of the unit incapable of moving backward, the brakes thereof operate for example. Moreover, when the operator turns the wheel 4 in a clockwise direction (in the direction of arrow C), the radio controlled unit turns to the right in conformity with the degree of the turn. Likewise, when the operator turns the steering wheels 4 in a counterclockwise direction (in the direction of arrow D), the radio controlled unit turns to the left in response to the degree of the turn. Accordingly, by manipulating in combination the throttle trigger 3 and the steering wheel 4, the user can remotely control the radio controlled unit.
Furthermore, the radio control transmitter of this sort is further provided with a mechanism to regulate controlled variables in controlling the radio controlled unit based on the control inputs of the throttle trigger 3 and the steering wheel 4. More specifically, the controlled variables can be regulated by controlling the neutral position and the maximum rudder angle (maximum operating range) for each of the speed control servo and the direction control servo that operate in response to the amount of inputs of the throttle trigger 3 and the steering wheel 4. Such task of controlling the neutral position and the maximum rudder angles of the servos are carried out by switches that are conventionally located near the throttle trigger 3 and the steering wheel 4, so that such control can be carried out while remotely controlling the radio controlled unit. Referring to the radio control transmitter illustrated in FIG. 8, the adjustment of the neutral positions of the servos for controlling the speed and the direction is performed by utilizing switches 8 provided near the steering wheel 4, wherein there are three switches 8 provided in a top vertical portion and left and right horizontal portions with respect to the axial line of steering wheel 4. One of the switches 8 is installed for adjusting the neutral position of the speed control servo and another for adjusting the direction control servo. The adjustment of the rudder angles (maximum operating range) of the speed control servo and the direction control servo is performed by utilizing a dial 9 placed near the throttle trigger 3, enabling the user to remotely control the radio controlled unit while observing its motion.
Although the switches 8 described above are disposed near the steering wheel 4 to be operable while remotely controlling the radio controlled unit, they are rigidly fixed to pre-specified locations. Despite such configuration, users come from various age groups ranging from a child to an adult, each having different hand holding postures and grips. In particular, with users having various grips, certain users may encounter a great difficulty especially in operating rigidly fixed switches while holding the steering wheel. Accordingly, such configuration may pose great difficulties in controlling the neutral position or the maximum rudder angle while manipulating the steering wheel. Consequently, operating the radio controlled unit under such configuration may force the user to lose control thereof. In case of a model car being controlled by the radio control transmitter under such configuration, the model car may incur collisions with walls or other obstacles for lack of control the user has thereon with such radio control transmitter.
Recent trends show operability of such radio control transmitter has been improving. By interposing an adapter between the main body and the steering wheel, the steering wheel can be placed at positions other than the conventionally pre-determined position (at the center of the front face). In general, the position of the steering wheel is adjusted with the adapter to about the height of the throttle trigger. However, even with such adapters allowing for an adjustment of the location of the steering wheel, there is a need for an easily accessible and operable switches.